Wind power is considered one of the cleanest, most environmentally friendly energy sources presently available, and wind turbines have gained increased attention in this regard. A modern wind turbine typically includes a tower, a generator, a gearbox, a nacelle, and one or more rotor blades. The rotor blades capture kinetic energy from wind using known foil principles and transmit the kinetic energy through rotational energy to turn a shaft coupling the rotor blades to a gearbox, or if a gearbox is not used, directly to the generator. The generator then converts the mechanical energy to electrical energy that may be deployed to a utility grid.
The particular size of wind turbine rotor blades is a significant factor contributing to the overall efficiency of the wind turbine. Specifically, increases in the length or span of a rotor blade may generally lead to an overall increase in the energy production of a wind turbine. Accordingly, efforts to increase the size of rotor blades aid in the continuing growth of wind turbine technology and the adoption of wind energy as an alternative energy source. However, as rotor blade sizes increase, so do the loads transferred through the blades to other components of the wind turbine (e.g., the wind turbine hub and other components). For example, longer rotor blades result in higher loads due to the increased mass of the blades as well as the increased aerodynamic loads acting along the span of the blade. Such increased loads can be particularly problematic in high-speed wind conditions, as the loads transferred through the rotor blades may exceed the load-bearing capabilities of other wind turbine components.
Certain surface features, such as spoilers, are known that may be utilized to separate the flow of air from the outer surface of a rotor blade, thereby reducing the lift generated by the blade and reducing the loads acting on the blade. However, these surface features are typically designed to be permanently disposed along the outer surface of the rotor blade. As such, the amount of lift generated by the rotor blade is reduced regardless of the conditions in which the wind turbine is operating.
Additionally, U.S. Pat. No. 4,692,095 describes wind turbine blades with active spoilers on the low pressure side of the blade that rapidly deploy to control an overspeed condition. The spoilers are connected to an electrically operated clutch, which normally holds the spoilers in a flush-mount position. In an overspeed condition, the clutch releases the rope and the spoiler opens via a spring. The spoiler, however, opens against the force of the airflow over the blade and the spring must be of sufficient size and strength to hold the spoiler open as the rotor slows. Likewise, the clutch must be of sufficient size and power to retract the spoiler against the force of the spring.
Accordingly, the industry would benefit from a wind turbine rotor blade having a simple and cost-effective actuatable spoiler to reduce lift. More specifically, a rotor blade having an actuatable spoiler with a living hinge would be advantageous.